I found this bug to on a client's site. Forcing a logout seems to fix it.
So, I put a forced logout in the function resend function, just after it sends the activation link.
The working code looks like this in application/controllers/auth.php
function send_again()
{
if (!$this->tank_auth->is_logged_in(FALSE)) { // not logged in or activated
redirect('/auth/login/');
} else {
$this->form_validation->set_rules('email', 'Email', 'trim|required|xss_clean|valid_email');
$data['errors'] = array();
if ($this->form_validation->run()) { // validation ok
if (!is_null($data = $this->tank_auth->change_email(
$this->form_validation->set_value('email')))) { // success
$data['site_name'] = $this->config->item('website_name', 'tank_auth');
$data['activation_period'] = $this->config->item('email_activation_expire', 'tank_auth') / 3600;
$this->_send_email('activate', $data['email'], $data);
$this->_display_message(sprintf($this->lang->line('auth_message_activation_email_sent'), $data['email']));
/*
* Force a logout here or tank_auth remains
* stuck in the resend mode.
*/
$this->tank_auth->logout();
} else {
$errors = $this->tank_auth->get_error_message();
foreach ($errors as $k => $v) $data['errors'][$k] = $this->lang->line($v);
}
.....
As far as I can tell, this is just hack, but it solved the problem for me. I don't know if the creator of this site changed anything or not in the tank_auth actions.
I hope it works for others.